Electric plug



Oct. 5,y 1948. M. M. GUERNSEY ELECTRIC PLUG Filed May 13, 194'? i zz I 2 INVENToR.

Max N Gz/msey Patented Oct. 5, A1948 UNITED S TAT ES PATENT OF FICE.

ELECTRIC PIUG' Max M-. Guernsey, Steilacoom, Wash.-

Ap'pli'cat'on May' f3, 19M-,Serial No. 747,613

4 Claimsl (Cl. 1734-361) This invention relates' to electric plugs/adapted to be attached to the four wires from the terminal box of an electric motor, and especially to such a plug as maybe connected to either a 11'0-l voi't or'220-volt supply circuit and will automatically make connections between either of saidv supplyv circuits and the proper' wires to the motor, and more particularly is an improvement on the form-of plug patentedy by me on March; 25, 1947, numbered 2,417,928.

The objects of my invention are to improve the construction of such a plug as illustrated in my said patent, whereby the,k plug is made stronger and more substantial; whereby the exposed terminai prongs cannot be incorrectly inserted in the particular circuit outlet; whereby' a ground connection is provided for the 22o-volt outlet; which is simple in construction and unfailngly makes the correct motor connectons for the par-- ticular supplyci'rcuit to which it is tobe applied; and. in which the attaching screws for'the' several motor wires are conveniently located and arev of' ready -access forV tightening.

I attain. these land other objectsi as` will readily appear to' those familiar with the art, bythe devices, and.' arrangements illustrated in thek accom#- panying drawings, in which Fig.. 14 is aplan. viewv of the end of the: plug; with its. cover removed; Fig. 2 is a vertical cross-` section thereof, taken on the line 2'2 iritli'gg-l;` Fig; 3f is a similar View, taken on the line 3.-3. in Fig; I.; Fig. 4. a plan View ofthe 22H-'volt side ot the insert member; Fig. 5` is a similar viewv of; the 11G-volt side thereof; Fig. 6 is a side elevation. of the insert member; Fig. 'l is a section thereof taken on the line in Fig. 6 Fig. 8 isY a plan. view of' the cover; and Figs.v 9 and. l0 are diagrammatic Views. of the connections between the` motor wires and the contact prongs for the 11G-volt and 220voltsupply circuits, re-V spectively.

Similar numeralsof referencey refer to the same parts throughout the several views.

Small electric motors are adapted' to be connected either to a 11G-volt or to a 220-volt supply circuit and are provided with four live Wires circuit.. the wires |10 l and lll-Z- mustbefconnected f motor' toa 22o-volt supply crcuit,vthe Wires |02 and |03are connected together, the wire |0'| is. connected to onel'contact' prong and thewire 4 104 is connected tov thev vother prong, while the ground wire |00 i's connected Ito a third contact pI'OIl'g.

The main body I0 of the plug is formed'oif' hard rubber, or of other suitable insulating material,

as'- seen in Figs. 1 andi 8, and its interior isdivided into. lthree distinct" chambers connected together.

The chamber lli is preferably cylyiridri'cali in form and forms lthe entrance passagev by which the rive wires of the: motor enter' theiplu'g.

immediately above the cham-ber I form a central chamber |12; which is deepenou'gh to receivethe prongs oi: the insert'v member' hereinafter described. This chamber |-2 is provided with a metallicr contact 3,. extending. upright therein and adapted to contact they-ground prong.` of the 22m volt side of Ithe insert member, as hereinafter described.

This contact plate I3 is. electrically connected by av suitable conductor to a terminal I4 on the outside of' the plug` |10, said terminal |.ll` being` adapted to be connected to -a suitable ground. This. chamber IZ isf of'v such. form as lto' receive the several prongs of the insert member and is, in general, rectangular inform (Fig. I) but with two.- sidecavities |152 adapted. to receive: the. inf clined prongs or theI 22o-volt: side `of the insert member. Y

The upper chamber' |16. is adapted: to.' receive: the insert member, the contact prongs of one side thereof. extending down into the chamber` l2, while Ithose of the other sfde thereof project up"- ward through suitable openings in the-cover` which is: removably secure-d to the bodyA |'0A and which closes the said chamber IS; This chamber |6 is larger than the chamber I2, thus leaving a shelf." |8 extending; around'r threer sides'thereof. The form of the cham-ber I6. follows closely that of. the.` body |0= except at one end whichl is' not curved;` thus preventing the similarly shaped intherein..

shelf I8.` hase-five: metal `plates secured.

thereon, each of which extends up the sides of the chamber. The part of the said plates resting en the shelf I8 is provided with a screw by means of which Vthe wires from the motor are attached to the plates.

The ground wire is thus attached to the plate I9; the wire |0| is fastened to the plate 20; the wire |02 is fastened to the plate 2|; the wire |03 is fastened to the plate 22; and the wire I 04 is fastened to the plate 23. The plates 20 and 23 are located on opposite corners of the same side shelf I8; and the plates '2| and 22 are located near the center of the shelf I8 on the opposite side of the chamber I6. The ground wire |00 leads from the motor and is fastened to the plate I0 which is located at the center of the curved end of the chamber I6. As above described, a second ground plate I3 is secured in the middle of the same 'end of the chamber I2 and has a connection leading through the body |0 to a terminalscrew I4, to which a grounding wire may be secured.

These contact plates 20, 2|', 22 and 23 are positioned in the sides of the outer chamber I0 in staggered relation on the two opposite sides of the chamber so that, when the hereinafter described insert member is inserted into the outer chamber, the side plates thereof will contact different contact plates when one set of prongs thereof are exposed for use, than when the other set of prongs are exposed for use, thus making different connections within the said insert member between the exposed prongs and the motor wires, to suit the different voltages of the supply circuits.

The insert member 24 comprises a body made of hard rubber or other suitable insulating material, shaped to t neatly in the upper chamber I6. The insert member has two prongs 25 and 26 extending in parallel positions from one side thereof; and two other contact prongs 21 and '28, set at an angle to each other, extending from the opposite side thereof.

The insert member 24 is also provided with a third, or ground, contact prong 29, extending from the same side as the said prongs 21 and 28, and which is adapted to ground the outlet when the insert member is set for the 220-volt supply circuit.

All the above contact prongs extend into the insert member to the central plane thereof. This central plane is illustrated in Fig. '1 of the drawing, showing the ends of the several prongs 25, 20, 21, 28 and 29. The sides of the insert member are provided with five contact plates which are `connected by suitable conductors to the several prongs as follows: The prong 25 is conncctedto the side plates 30 and 3| at the upper corners of the insert member, and also to the prong 21. The prong 26 is connected to the side plate 32, which extends across the lower side'of the insert member and around the two lower corners thereof, and this plate 32 is also connected to the prong 28. The prong 29 is connected to the plate 33 positioned at the center of the curved end of the insert member 24. An unattached side plate 34 is positioned at the center of the same side as the side plate 30.

When the motor is to be connected to the 110- volt supply circuit the two prongs '25 and 26 project through the cover I1 and are positioned to enter the corresponding openings in the 11G-volt supply circuit outlet. The prong 25 thus connects to both the side plates 30 and 3 I, and these plates contact the plates 20 and 2| in the chamber I6, to which the motor wires I0| and |02 are connected. The other prong 26 connects to the` side plate 32, which contacts the plates 22 and 23 in the chamber and these plates are connected to the motor wires |03 and |04.

When the insert member is in this position the ground prong 29 extends down into the chamber |'2 and the side plate 33 thereof contacts the grounded plate |0, while the prong 29 cotacts the plate |`3 which is connected to the ground terminal I4. When the insert member is in this position the said two other prongs 21 and 28 lie in the chamber I2, lying in the side cavities I5 therein. Thus it will be seen that the two wires |0| and |02 are joined together at the removable prong 25, through the plates 20, 30 and2I, 3|; and that the wires |03 and |04 are 'similarly joined together at the prong 26 through the plates 22, 32 and 23.

When, however, the motor is to be connected with a 22o-volt supply circuit the insert member 24 is inverted in position in the chamber I6,

r is connected to the end side plate 33 which contacts the ground plate I9, which is connected to the motor ground wire |00. The prong 21 is connected to the side plate 3| which contacts the plate 20 to which the motor wire |0I is connected; the prong 28 is connected to the side plate 32 which contacts the plate 23 to which the motor wire |04 is connected; and the motor wires |02 and I 03, connected to the plates 2| and 22, re spectively, are electrically joined together by the contact with the side plate 34.

Thus it will be seen that I have invented an improved plug in which the insert member mustbe in either of two inverted positions, and the contact plugs extending therefrom being such as tc make the correct connections between the motor wires for the particular supply currentvoltage. It will be further observed that this4 form of plug is of very substantial and rugged construction and is suitable for practicaluse under factory conditions. Further, the fact that the outer chamber is larger than the centralV chamber, thus providing a shelf between the4 two chambers, not only gives la firm base for the insert member to receive the pressure from the exposed contact prongs when they are being inserted inthe supply outlet, but also gives a horizontal base for the several contact plates I9 to 23 so that the screws securing the several wires of` ,th,e motor to said plates act downward and are convenient of access by the screw driver when the several wires are being secured thereto, or the screws are being tightened thereon.

It is,`of course, to be understood that changes may be made in the detalls of construction of the above described electric plug without departing from the spirit of my invention as outlined in the appended claims.

Having, therefore, described my invention,

what I claim and desire to Vsecure by Letters conductsaid wires thereinto; an outer chamber having ve insulated contact plates secured therein, said wires being secured to said plates; an insert member of insulating material adapted to be placed in said outer chamber in either of two inverted positions; five contact prongs extending from the two opposite sides of said insert member, onev set thereof extending into said central chamber and the other set thereof extending out from said plug for engagement with one of said supply circuits; insulated contact plates mounted on the sides of said insert member and connected to said contact prongs, and adapted to severally contact with said contact plates in said outer chamber, whereby the said contact prongs are electrically connected to said wires.

2. An electric plug as set forth in claim 1, wherein said outer chamber is of larger dimensions than said central chamber, thereby providing a shelf between the two said chambers, whereon said insert member is based.

3. An electric plug as set forth in claim 1, one of said ve wires is a ground wire; wherein one of said Contact plates is a ground contact plate mountedon the shelf in the center of the end of said outer chamber and connected to said ground wire; wherein one of the prongs is a ground prong.

extending from one side of said insert member; a side plate secured to the end of said insert member, and connected to said ground prong, whereby said ground plate in said outer chamber will engage said end side plate on the insert member when said insert member is in either of its two positions.

4. An electric plug, comprising a plug body; a

chamber in the end thereof; a plurality of xed plates mounted in said chamber, .to which a plurality of wires are secured; an invertble insert member in said chamber; means to limit the position of said insert member in said chamber; a plurality of contact prongs extending from the upper and lower sides of said insert member; a 'plurality of side plates centrally mounted on the sides of said insert member, certain of said side plates being electrically connected to said prongs,

said side plates being adapted to contact said xed plates, whereby the relative contact between said fixed plates and the side plates, and the exposed prongs, are changed when the said insert rnember'is inverted.

MAX M. GUERNSEY.

.REFERENCES CITED The following references are of record in the le of thispatent:

UNITED STATES PATENTS 

